Remove ui/ directory from build/secondary.

This directory contains a GN build file that defines a dummy "ui"
component target that does not really do anything that matters.

ui/ targets are almost finished at this time, so there is no point in
keeping this ui/ BUILD file in build/secondary.

BUG=None
TEST=None
R=brettw@chromium.org
NOTRY=true

Review URL: https://codereview.chromium.org/451553002

Cr-Commit-Position: refs/heads/master@{#290188}
git-svn-id: svn://svn.chromium.org/chrome/trunk/src@290188 0039d316-1c4b-4281-b951-d872f2087c98

build/secondary/ui/BUILD.gn

-# Copyright 2014 The Chromium Authors. All rights reserved.
-# Use of this source code is governed by a BSD-style license that can be
-# found in the LICENSE file.
-
-component("ui") {
-  # TODO(brettw) do this target, this current stuff is only to make Chrome
-  # link.
-
-    configs += "//build/config/linux:x11"
-  }
-}